Rapid alterations in glucose transport and metabolism have been shown in rat adipocytes after fasting and refeeding. The mechanism for this was examined in rats fasted for 48 h and sacrificed within 6d of refeeding. The results suggest that insulin resistance at the glucose transport level induced by fasting is due to a depletion of intracellular glucose transporters. In contrast, the hyperresponsive insulin-stimulated glucose transport activity associated with refeeding is not totally accounted for by a change in the number of glucose transporters and may also involve modulation of glucose transporter intrinsic activity.